Nov. 16, 2013

Coal-tar sealcoat is used on many commercial parking lots in the Upstate. / NATHANIEL CARY / STAFF

Written by

Nathaniel Cary

Staff Writer

Coal-tar sealcoat is sprayed on a parking lot as part of U.S. Geological Survey research. / Provided by USGS

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A common pavement coating applied to parking lots and driveways across South Carolina to protect asphalt from wear contains a toxic and highly potent carcinogen that’s been linked to cancer.

Yet across much of the East Coast, the practice of adding a sealcoat to pavement continues as the predominant way for schools, businesses, churches and homeowners to protect their driveways and parking lots from wear.

A growing number of cities, counties and states across the country have passed bans on using the controversial materials, and now the city of Greenville has enacted its own ban on coal-tar pavement sealcoats.

The sealant remains in use throughout the rest of the state by paving contractors who have used it for decades to provide the shiny, black finish to parking lots and driveways. The product seals water out and keeps asphalt from developing cracks.

Federal studies performed across the country have shown that the sealcoat wears off and makes its way into waterways where it harms aquatic life. Coal-tar sealcoat also can rub off from friction from shoes or car tires and then wind carries the carcinogens into nearby buildings, studies show.

Living adjacent to coal-tar sealed pavement is estimated to increase lifetime cancer risk 38 times, according to a group of U.S. Geological Survey hydrologists who’ve studied the effects of coal-tar sealants.

Distributors of the product say the issue is overblown, the product can’t definitively be linked to cancer, and the science is flawed.

But government studies that have been published in peer-reviewed journals suggest otherwise, saying the chemicals are concentrated close to coal-tar sealcoat sources, are causing irreparable harm to urban lakes and streams and are elevating human health risks.

The liquid sealcoat is sprayed or painted onto driveways or parking lots, and while many national home-improvement chains have stopped selling the product, paving contractors continue to use it.

Due to cost, the sealcoat isn’t used on roads.

Coal-tar sealcoats contain polycyclic aromatic hydrocarbons, or PAHs, a group of chemical compounds found when coal, tar or oil are burned, and can be found in wood fires, backyard barbecues, cigarette smoke or used motor oil.

Government studies show that the amount of PAHs found in coal-tar pitch, a main ingredient of coal-tar sealcoat, far outweigh what would be found in most sources. Coal-tar pitch contains more than 50 percent PAHs by weight, 150 times the amount found in used motor oil, studies found.

PAHs have been labeled as toxic pollutants by the Environmental Protection Agency and can cause birth defects, harm early-childhood development and damage aquatic life, according to the USGS and EPA. Several PAHs are listed by the EPA as probable cancer-causing human carcinogens.

The issue has pitted industry against science, and it has resulted in a piecemeal approach to reducing the use of coal-tar pavement sealers across the eastern half of the U.S., where the sealcoat is primarily used.

In the Southeast, Greenville joins Boone, N.C., as the first places to enact a coal-tar sealant ban.

Accidental discovery

Federal researchers based in Austin, Texas, stumbled upon the possibility that coal-tar sealcoats were responsible for high levels of the toxins found in lakes they were studying across the country. They saw that PAH levels were increasing in urban lakes and sought to determine the cause.

“Scientists, we’re really just detectives,” said Barbara Mahler, a USGS research hydrologist based in Austin. “There are mysteries and we go out and look for clues and we try to figure out what’s happening. This increase in PAH was a mystery to us, and that’s really what sent us up the watershed to figure out where they were coming from.”

In some Austin creeks, they found PAH levels that were “superfund-site high” and traced the sources to nearby parking lots and eventually to the sealcoat, Mahler said.

Quickly, they realized the toxic levels weren’t limited to Austin. These sealcoats were being used across the entire eastern half of the country.

Much of the western half of the country uses an asphalt pavement sealer, which is oil-based and contains much lower levels of PAHs than coal-tar sealant.

Subsequent studies showed that emissions of the chemicals into the air from sealed parking lots are 60 times higher than unsealed parking lots. Another USGS study showed that sealcoat is the largest source of PAH contamination of 40 urban lakes studied across the country.

So far, the EPA and many states, including South Carolina, have not banned the sealcoat.

That could be due to industry lobbying, said Dave Hargett, principal of HRI Environmental Consultants and executive director of the Lake Conestee Foundation, who has studied the effects of PAHs on Lake Conestee.

Still, the states of Washington and Minnesota have banned coal-tar sealcoats, as has Washington, D.C., counties in Wisconsin, Maryland and New York and at least 15 cities across the U.S.

South Carolina’s Department of Health and Environmental Control has taken no particular stance on the issue, said Jim Beasley, DHEC spokesman. He said it was strictly a local issue.

A Representative from Texas introduced a bill in the U.S. House to outlaw coal-tar sealcoat in 2012, but it was referred to committee and hasn’t been debated.

The EPA has begun to perform its own studies on the effects of the sealcoat. In 2011, the EPA used a test site to study runoff from sealed and unsealed parking lots. It found that runoff from pavement recently sealed using the coal-tar based product had 100 to 1,000 times more PAHs than the other surfaces.

Greenville's ban

At Greenville’s lake-in-recovery, Lake Conestee, PAHs can be found throughout the sediment that’s built up and filled in the lake through the decades, Hargett said.

Much of the toxins are the legacy of two shuttered coal-gasification plants that were located upstream in Greenville a century ago, he said.

In enough quantity, the toxins would be enough to designate a site as toxic on their own, but PAHs are usually found along with a multitude of other toxins in sites like Conestee, which has acted as the sponge that soaked up Greenville’s industrial contaminants over the decades, he said.

At Conestee, it would be difficult to separate which PAHs come from coal-tar sealcoats and which come from the closed coal plants, Hargett said, but he applauded Greenville’s efforts to ban the contaminants.

“It doesn’t help us cure the old problems we have already accumulated, but it helps us keep, at least, the spatial sediments and the surface environment which is thriving ecologically at Lake Conestee from being continually doused with new exposures to those kinds of chemical products,” Hargett said.

Greenville included the ban in its latest stormwater management ordinance, which passed with little fanfare in September. It simply reads, “The use of coal-tar based pavement sealcoat is prohibited.”

Jennifer Wood, senior civil engineer for Greenville, said Greenville included the ban after becoming aware of the government studies and action taken elsewhere to ban the product.

The ban does not require existing sealcoat to be removed, Wood said.

Greenville did not perform its own studies because it relied on the federally backed research, Wood said.

“We try to go off of federal and state standards,” she said. “We’re not just hanging it on some arbitrary study that’s out there. They’ve published a lot of data.”

A team of Clemson University students, led by Peter Van den Hurk, an associate professor of biological sciences, did perform tests on fish in urban Greenville and Easley streams and compared them to fish in non-urban Upstate streams. They found a much higher concentration of PAH toxins in the urban fish, though his research did not focus on the source of the contaminants, he said.

Industry pushback

Reaction to the ban brought a mix of emotions from local contractors, many who have used the product their entire careers.

One local contractor, Billy Tollison, said he doesn’t like to use the product himself because it can burn upon contact. Though he said he didn’t know about the cancer risks until recently, it’s made him wonder about friends in the business who’ve died from cancer.

Coal-tar sealants cannot be directly linked to cancer, said Bob Krebs, owner of Sealmaster Carolinas, which operates eight storefronts that sell coal-tar sealcoat and other pavement products. Krebs said he manufactures the sealcoat in his Madison, N.C., facility.

“As an owner, I don’t want to create any health hazards for anybody on this earth,” Krebs said. “When I leave this earth, I want to leave it in better shape than I’ve got it.”

The chemicals in question are everywhere — in power plants, fires, runoff from oil leaks, Krebs said.

“These, in my opinion, are gross exaggerations of the emissions of PAHs coming out of refined coal tar,” he said.

Krebs and local contractors cited research done by coal-tar industry lobbyist Pavement Coatings Technology Council that concluded PAH levels hadn’t gone down significantly in Austin watersheds in the years since the sealcoat was banned.

That’s not surprising, said Mahler, the USGS hydrologist, because PAHs have a long half-life, attach themselves to sediment and reside on the bottoms of rivers and streams.

It’s similar to the way polychlorinated biphenyl, or PCBs, have been difficult to get rid of in the Twelve Mile River arm of Lake Hartwell over several decades. It takes time for clean sediment to cover the contaminated soil, she said.

Anne LeHuray, executive director of the Pavement Coatings Technology Council, said they’ve started to file challenges to the USGS data. She said the studies would not have received as much attention if they had not been performed by government scientists.

Mahler said her agency does not advocate, does not take positions and is not a regulatory agency, so there’s no reason for it to show bias against the coal-tar industry.

“Our job is to be the detectives,” she said. “When we have identified a problem, something like a type of contamination, then our job is to try and determine what’s causing it.”

Effect on contractors

Jason Owens has owned Carolina Sealcoating since 2006. He worked with his dad’s company for years before that, and he’s regularly done work in the city limits of Greenville.

Until now.

“I just turned two people that I have been doing business with for the past seven or eight years away in the past two weeks because of this,” Owens said. “I will not change products.”

Owens is angry that the city didn’t inform him of the potential ban before it enacted the ordinance.

Wood, with the city, said Greenville publicized the ordinance and debated it just as it does every other law change.

Owens said he has zero concern about getting sick from using coal-tar based products. He said he’s tested the asphalt-based product, and he called it more costly and less durable than the coal-tar sealcoat.

Eric Taylor, owner of Taylors Sealcoating and Striping, said he’s equipped to use asphalt-based sealcoat on Greenville projects, but said some contractors may have to change equipment because the product must be mixed differently.

Krebs, the franchisee with Carolina Sealmaster, said he sells the asphalt-based sealcoat in his Greenville store, and some like the flatter black sheen better than the glossy finish of the coal-tar sealcoat. It does take some training to use it correctly, he said.

Krebs said the spreading of coal-tar sealcoat bans would lead to further elimination of jobs in coal states.

If more places follow Greenville’s lead to ban coal-tar sealcoat, Owens said it would lead to the end of the pavement rehabilitation industry.